OpenSystemsDevelopment / usbboot

mass-storage-gadget: Remove activity LED for CM3 compatibility

Merge https://github.com/timg236/cm4-scripts/pull/1 to remove the
LED activity flashing because this conflicts with EMMC_EN_N_1V8
on CM3.

I've reverted the change that removed the explict modprobe of
libcomposite becuase that broke the gadgetfs support for me on CM4.